I want to believe some will move for lifestyle reasons, but the problem is the post war IPO landscape (post 1980s really) across biotech and ICT has made one stark barrier: USA is a place where you can go from $100k to $100m vesting if you are lucky. That very few do achieve this isn't the point: you cannot do it, in almost any other economy.
You have to be socially smart enough to see that a $100k salary and lifestyle outcome for your remaining working career is enough, if not better than the prospect of uplift into mega-wealth, if your IPR pans out the right way.
For career scientists who were on the NSF grant train, they'd cracked a magic egg open. Beneficial to both them and us, society at large. Well, the other economies do fund research. They fund it badly compared to the NSF, the paperwork burden is less I am sure, but so is the size of the pot and the duration. You may well spend more time hassling next grant, than doing the grant funded work.
I've known US scientists who moved to my economy (OZ) and they say its a great place to live, but they keep ties to US funded research because its what made them attractive to the non-US university or corporate research environment. If that tie is going to be cut, they're competing against one quality only: skill. Sure, a more level playing field. But that, and english language competency aside, it will be a competition against scientists from the rest of the world, who also used to go to the USA and now are seeking jobs in other economies.